1. Field of the Invention
The present invention relates to a bellows pump and more particularly to a bellows pump to pump a fluid or to use as a compressor and an actuator.
2. Description of the Related Art
In general, a bellows pump has a pumping action according to the expansion and contraction of a bellows. A pumping room of the bellows pump comprises the bellows and a housing. The bellows has some peak portions and each peak portion has a fixed thickness and a fixed pitch. One end of the bellows is fixed to a stationary member and the other end thereof is fixed to a movable member. Here, the bellows is repeatedly stressed when the bellows expands and contracts and when the bellows receives a pressure of a pumped fluid. Therefore, the bellows is of poor lasting quality.
On the other hand, when a driving speed of the bellows is low, all of the pitches of two adjacent peak portions vary equally. However, when the driving speed is high, the pitches of two adjacent peak portions differ depending on a location of each peak portion. Namely, when the bellows expands, excessive pitches are shown in some portion, and when the bellows contracts, too little pitches are shown in some other portion. As a result, the stress of the bellows increases in high speed driving condition, and the bellows is of poor lasting quality.